bTB Cull

Currently, thousands of cattle are slaughtered every year (30,000 in 2010) because of bovine tuberculosis (bTB) – an airborne respiratory disease – at enormous cost to farmers and the taxpayer: £100m in 2010. Badgers are often blamed for this, although there is no conclusive evidence that badgers pass bTB to cattle, or how, even though there are indications that they can, and vice-versa.

Given the financial losses to farmers and the taxpayer because of cattle being slaughtered prematurely, and farmers being paid compensation, the government wants to carry out a cull of badgers in certain areas in an effort to control bTB.

Last year, the government lost a debate in parliament on the issue, when the votes of the house were 147 against a cull and only 28 in favour. It then said it was postponing the cull for practical reasons, but has since said that it does intend to go ahead with a cull in 2013, despite massive public opposition and campaigns from the Badger Trust, Team Badger (led by former Queen guitarist Brian May), the League Against Cruel Sports, the RSPCA, leading conservationists, etc.

The history of the disease goes back a long way. Bovine TB was almost eradicated by 1970, when there were only about 1,000 cases. Eleven years of localised badger culling failed to reduce the toll further. But the end of annual cattle testing in the mid-80s, and the devastating effects of BSE and foot-and-mouth disease, when testing was abandoned altogether, meant that many farms lost thousands of animals, and afterward there was a rush to restock. Regulations were relaxed, so cattle were bought and sold and – crucially – moved all over the country. Bovine tuberculosis was back. These relaxations of the movement and testing regimes contributed to the upsurge in cases of bTB in cattle.

So, to the question of whether badgers are responsible for increasing infection rates in cattle. If they are, how have cattle remained free of bTB in Scotland, where no badgers have been killed? Why do they have it in the Isle of Man, where there are no badgers? And why are bTB rates twice as high in Ireland, where so many badgers have been killed that they are extinct in many areas?

Could it be possible that cattle are infecting badgers? After all, cattle far outnumber badgers – 9 million cattle to, at most, a quarter of a million badgers.

George Pearce, a wildlife consultant, used to be a farmer. In his new book, Badger Behaviour, Conservation and Rehabilitation: 70 Years of Getting to Know Badgers, he explains how his family's farm, which always had badger setts on it, managed to remain free of bTB from 1950 to 2008, when the herd was dispersed.

Since the 1930s, there have been four important measures used to combat bTB: very strict movement controls, thorough cleansing of livestock buildings, good ventilation and double fencing on all boundaries to prevent cattle in adjoining fields from exchanging saliva.

Pearce says that if we want to solve this crisis, we should be talking about cattle, not badgers.

Aside from these measures, he suggests that we look at the bloodlines of our cattle. All bulls, whether used naturally or artificially, should have blood tests to assess their susceptibility to bTB. The reduced gene pool of bulls over the past 60 years could be contributing to the problem.

Cattle that were largely bTB-free in the 60s and 70s, he adds – mostly British breeds – have gradually been replaced by continental breeds. Are they less resistant?

What's more, cattle are bred much more intensively now, and bTB is known to be a stress-related disease.

What about dietary deficiencies? Dick Roper in Gloucestershire was anxious to find out why one of his farms was hit by bTB when his others were not. On the affected farm, the cattle were fed on maize, which badgers also love. But maize lacks selenium, a mineral that – in humans and livestock – is necessary to maintain a strong immune system. So, Roper introduced selenium mineral licks for his cattle, and for the badgers on his land – to the amusement of his neighbours – and cured his problem, despite all the farms around him becoming infected. Are cattle getting bTB because their immune system is compromised?

In the past two years, improved cattle testing, biosecurity and movement controls in England have led to a 15% reduction in the rates of bTB infection. In Wales, during the same period, the number of cattle slaughtered because of bTB has fallen by 36%, and by 45% in Dyfed. The Welsh Assembly Government had proposed a cull, before being forced to drop the plan after a legal battle that was won by the Badger Trust. (It has since decided to opt for vaccination instead, and will also introduce additional cattle control measures from 1 April 2013. The vaccination project was carried out over an area of 242 sq km, mostly in north Pembrokeshire, but also in small parts of Ceredigion and Carmarthenshire. In its first year, 1,424 badgers were cage-trapped and vaccinated, and the Welsh government confirms that it plans to expand the project to increase coverage in future years.)

In 2010, the coalition government announced a public consultation on whether we should have a cull. Of those who responded, 69% were against a cull and 31% were in favour of culling, but alongside vaccination. 

In other polls, too, the public made their opposition clear: 97% against in a 2007 poll for the Labour government; 68%, both rural and urban, against in a recent BBC poll90.9% against in a Guardian poll in July 2011. Even a survey by Countryfile, which largely has a farming audience, polled more than 60% against a cull.

All the evidence points to the fact that a cull would not help to reduce the incidence of bTB. To support this conclusion, we need only look back at the evidence of the Krebs trial, a massive pilot cull of badgers over 10 years between 1997 and 2007, overseen by the Independent Scientific Group (ISG). The trial showed that bTB in the culling area was reduced only marginally. Outside the culling area, it actually rose, a result of what is called perturbation, where badgers who have survived a cull spread out to escape danger. This behaviour does not occur in any other species. The conclusion of this massive trial was that "culling can make no meaningful contribution to the reduction of bTB".

In the weeks leading up to the government's announcement of a proposed cull, seven former members of the ISG wrote a letter to the Times opposing it. They included Lord Krebs, who designed the 10-year trial and is now chairman of the House of Lords science and technology select committee, Professor John Bourne, the ISG's chairman, and Dr Chris Cheeseman, the principal scientist for many years at Defra's Woodchester Park study area in Gloucestershire, where farmers themselves were involved in research into badgers, cattle and bTB. They said there was "no empirical data on the cost or effectiveness (or indeed humaneness or safety) of controlling badgers by shooting, which has been illegal for decades".

For the latest on the bTB debate, go to News: current situation.

This is an edited extract from a blog on the Guardian website. Read the original blog at:

http://www.guardian.co.uk/environment/blog/2011/aug/11/badger-cull-dont-stop-bovine-tb